JPH0857963A - Butt welding method for thermoplastic resin tube material - Google Patents

Abstract

PURPOSE: To provide a method for butt welding a thermoplastic resin tube material having high reliability of connecting strength. CONSTITUTION: Tube end faces 11a, 12a of a connecting tube material are formed in a shape inclined from the outer peripheral edge toward the inside in the inward direction of the tube. Thus, the boundary SA of a molten part WA generated at the tube end of the material and a non-molten part is but welded in the state of perpendicularly crossed with the axial direction of the material by heating of heater without contact, thereby uniformly applying a connecting load to the connecting surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting resin-molded pipe materials by butt welding, and more specifically, to thermoplastic resin pipe materials (for example, PPS) used for clean applications such as transportation of ultrapure water. : Butt welding method suitable for connecting polyphenylene sulfide moldings and the like).

[0002]

2. Description of the Related Art A method for connecting resin-molded pipes is to grasp the pipes with a pair of clamps, heat the ends of the pipes with a heater, and then move the clamps toward each other. There is a method of abutting and fusing each of the melted portions by performing the welding (for example, Japanese Patent Laid-Open No. 5-1
No. 93004).

Further, when connecting a pipe material formed of a thermoplastic resin such as PPS by this kind of butt welding, it is customary to melt the pipe end portion with a non-contact heater heating. Since the melting point of PPS is as high as 270 ° C., it is necessary to set the heater temperature to 300 ° C. or higher in order to heat the pipe end to a molten state. At such high temperature heating, the coating material on the heater surface is present. For this reason, contact heating makes it easier for the tube end surface to adhere to the heater surface.

[0004]

By the way, when the pipe end is melted by non-contact heating, when the outer diameter of the pipe material to be heated is relatively small with respect to the surface area of the heater hot plate,
Since the amount of heat received by the outer part of the pipe end surface is larger than that of the inner part, the outer surface of the pipe is heated rapidly and uneven heating occurs in the wall thickness direction (radial direction) of the pipe end, resulting in uneven melting of the pipe end. May occur.

When such a deviation in the amount of melting occurs, the bonding load at the time of bonding is concentrated on the inner portion of the pipe where the melting margin is small, and no load is applied to the outer portion, resulting in a reduction in the bonding strength. A problem such as, occurs.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a butt welding method for a thermoplastic resin pipe material having high reliability of joint strength.

[0007]

In order to achieve the above object, the method of the present invention corresponds to the embodiment shown in FIGS.
As shown in (A), the heater 3 is arranged between the pipe end faces of the pair of pipe members 11 and 12 for connection, and each pipe end portion is melted by non-contact heating. In a welding method of abutting pipe end faces with each other, a pair of pipe materials 1
By processing the respective pipe end surfaces 11a and 12a of the pipes 1 and 12 into a shape that inclines inward from the outer peripheral edge toward the inside of the pipe, melting that occurs at the pipe end portions of the pipe materials 11 and 12 by the heater heating. Interface SA between the part WA and the non-melted part
Is a surface orthogonal to the axial direction of the pipe material, and in this state, the pipe materials 11 and 12 are butted.

Here, in the method of the present invention, the control amount for making the melting interface SA generated at the pipe end portion by the heater heating into the plane orthogonal to the pipe axis is the pipe end faces 11a, 12
The inclination angle of a, the heater temperature and the heating time thereof are used. Further, specific numerical values of these control amounts are previously obtained by experiments or the like using conditions such as the nominal diameter of the pipe material as parameters.

[0009]

First of all, when a pipe material whose pipe end surface is perpendicular to the pipe axis is heated in a non-contact state by using a heater whose surface area of the heater hot plate is relatively large with respect to the pipe outer diameter, As the temperature rises faster toward the inside of the pipe, the amount of melting on the outside of the pipe becomes larger than the inside of the pipe. As a result, Fig. 2 (B)
As shown in FIG. 5, the interface SB between the melted portion WB and the non-melted portion generated at the pipe end has a shape inclined with respect to the pipe axis.

On the other hand, the respective pipe end faces 1 of the pipe members 11 and 12
If 1a and 12a are shaped so as to incline inward from the outer peripheral edge toward the inner side of the pipe, even if there is a difference in the amount of melting between the pipe outer side and the pipe inner side, the difference is Since it is absorbed by the difference in the axial distance (difference between the outside and the inside) created by the inclination, by appropriately selecting the inclination angle, as shown in Fig. 2 (A), the melt interface SA is formed into the pipe material. The surface may be orthogonal to the axial direction of.

By thus forming the melting interface SA as a plane perpendicular to the pipe axis, during pressure welding,
As a result of the joining load being uniformly applied to the joining surface, the joining strength in the thickness direction of the joining portion can be made uniform.

[0012]

FIG. 1 is an explanatory view of an embodiment of the butt welding method of the present invention. First, the apparatus used to carry out the method of the present invention (the entire structure is not shown) comprises a pair of clamps 1 and 2 facing each other, and a heater 3 arranged between the clamps.

The heater 3 is slidably or rotatably arranged with respect to the main body of the apparatus, and has a pair of clamps 1 and 1.
It is possible to selectively move to two positions, an intermediate position (use position) of 2 and a position (standby position) where the clamps 1 and 2 do not interfere with each other.

In this example, as the heater 3, the heat plate is made of aluminum, and the surface of the heat plate radiates infrared rays (far infrared rays) having a wavelength of 5 μm or more at an emissivity of 80% or more, for example, Tetuzole B-. 66 (heat resistant paint; trade name, manufactured by Nippon Paint Co., Ltd.) is used.

Next, the procedure of the embodiment of the method of the present invention will be described. First, as shown in FIG. 1 (A), the pipe end faces 11a and 12a of the thermoplastic resin pipe members 11 and 12 to be connected are
Each is processed into a shape that inclines inward from the outer peripheral edge toward the inside. Further, the heater 3 is heated and maintained at a temperature suitable for heating and melting the tube end portion, for example, 470 ° C.

Next, the pipe materials 11 and 12 are attached to the clamps 1 and 2, respectively.
To secure each, and then the tubing 11 and 12
The heater 3 is disposed between the pipe end surface 11 and the heater 3
a and 12a are heated and melted. In addition, at the time of this heating, it is preferable that the tube end surfaces 11a and 12a and the heating surface of the heater 3 are not in contact with each other and are spaced by about 1 mm.
The distance may be 1 mm or more.

The above-described heating of the heater is performed for a predetermined time, and the melting interface S generated at the pipe end portions of the pipe materials 11 and 12 is obtained.
Let A be a plane orthogonal to the axial direction of the pipe material [see FIG. 2 (A)]. In this state, the heater 3 is removed from between the pipe materials, and the pair of clamps 1 and 2 are moved relatively to each other. , 12 are butt-joined to each other with a predetermined joining load and fusion-bonded [Fig. 1 (B)].

Next, specific numerical examples of the embodiment of the present invention will be described.
Hereinafter, description will be given with reference to FIGS. 3 and 4. First, the sample to be joined was a PPS pipe with a nominal diameter of 75 mm, and the pipe end surface of this pipe was chamfered at an angle of 5 ° [Fig.
(A)] and the sample without chamfering [Fig. 3 (B)], the tube ends were heated in a non-contact manner (interval = 1 mm) at a heater temperature of 470 ° C, and the temperature of each tube end was increased during the heating process. When the rise was measured, the results shown in the graphs of FIGS. 4 (A) and 4 (B) were obtained.

The temperature at the tube end of each sample is shown in FIG.
As shown in (A) and (B), thermocouples are placed at the outer and inner parts of the pipe at a distance of 1 mm from the end face of the pipe, and the temperature at each point TA, tA and TB, tB. Was measured.

From the above measurement results, in the case where the pipe end face is not chamfered, the temperature is 30 ° C. between the temperature TB on the outside of the pipe and the temperature tB on the inside of the pipe even after the heating for 60 seconds.
Although there was a temperature difference between before and after, by chamfering at an angle of 5 °, the temperature TA on the outside of the pipe was increased by heating for 60 seconds.
It was found that it is possible to suppress the temperature difference between the temperature tA inside the tube and the temperature tA inside the tube to around 2 ° C.

Therefore, by carrying out the method of the present invention, as shown in FIG. 2 (A), it becomes possible to make the melting interface SA a plane perpendicular to the tube axis, which results in the strength of the joint. However, uniform bonding can be performed in the thickness direction.

In the embodiment of the present invention, the hot plate of the heater is made of aluminum, but the material of the hot plate is not particularly limited and may be, for example, iron, brass, stainless steel or ceramics. Further, the heater may be either a cartridge type heater or a cast-in heater.

Further, in the above embodiments, a heater having a structure in which a heat-resistant paint that radiates far infrared rays with a high emissivity is applied to the surface of the hot plate is used, but the hot plate is generally made of aluminum alone or the like. It goes without saying that the present invention can be applied to a welding method in which a pipe end is heated in a non-contact manner by using a heater having a different structure.

In addition to PPS, the method of the present invention also includes, for example, PEEK (polyether ether ketone) and PES.
(Polyether sulfone), PET (polyethylene terephthalate), PVDF (polyvinylidene fluoride) or the like, which is suitable for butt connection of tubing formed of a high melting point thermoplastic resin.

[0025]

As described above, according to the butt welding method of the present invention, by heating each pipe end surface of the connecting pipe material into a shape inclined from the outer peripheral edge toward the inner side toward the inner side of the pipe, the heater heating is performed. Since the butt joining of the pipe materials is performed with the melting interface generated at the pipe end in a plane that is orthogonal to the pipe axis direction, the joining load is applied uniformly to the joint surface, which results in the thickness direction of the joint portion. The bonding strength at is uniform.
As a result, the reliability of the bonding strength is improved.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of the method of the present invention.

FIG. 2 is an explanatory view of the operation of the method of the present invention.

FIG. 3 is a diagram showing a temperature measurement position at a pipe end.

FIG. 4 is a graph showing a temperature measurement result of a tube end, and is a graph showing a temperature rise of the tube end with respect to heating time.

[Explanation of symbols]

 1, 2 Clamp 3 Heater 11, 12 Pipe material (made of PPS) 11a, 12a Pipe end face WA Melting part SA Melting interface

Claims (1)

[Claims] 1. A method of connecting tubing formed of a thermoplastic resin by butt fusion welding, wherein a heater is arranged between the end faces of a pair of pipes to be connected, and each pipe end is heated without contact. After melting by the above, in the welding method of abutting the pipe end faces of the pair of pipe members to each other, by processing each pipe end face of the pair of pipe members into a shape that inclines inward from the outer peripheral edge toward the inside , The interface between the molten portion and the non-melted portion generated at the pipe end portion of each pipe material by the heater heating is a surface orthogonal to the axial direction of the pipe material, and in this state,
A method for butt welding a thermoplastic resin pipe material, which comprises performing the above-mentioned butt welding.